Question : OWA (Outlook Web Access)

We're having some problems with our OWA.
We're able to use it just fine internally but the problem we're having is that we can't access it externally.
It has worked in the past.
The firewall were using is a Cisco ASA5510 (just added to the network)
When we attempt to connect to it externally, as email.xyz.com the page isnt found.
Im able to ping email.xyz.com externally and it reply back successfully.
We have other devices that are working find behind the new firewall.

What can it be?

Answer : OWA (Outlook Web Access)

IF you run a syslog server, this would be easy to diagnose.   There are plenty of free syslog servers out there.  I use Kiwi's free syslog server all the time.  

To enable Syslogging:

LOGGING ENABLE
LOGGING HOST INSIDE
LOGGING TRAP NOTIFICATIONS  

This log will give you oodles of info on the traffic, including anything that's blocked and what blocked it.